1. Field of the Invention
The present invention generally relates to a bone plate manufacturing method and, more particularly, to a bone plate manufacturing method adopted to craniofacial surgeries.
2. Description of the Related Art
Craniofacial surgery has been an important surgery among surgical operations and is directed to congenitally oral and maxillofacial malformation, acquired injuries (such as fracture), or facial defects caused by tumor excision. Generally, surgeons rely on a 2D (two-dimensional) computerized axial tomography (CT) scan or a computer-established 3D (three-dimensional) craniofacial model to proceed preoperative tasks prior to craniofacial surgery. Then, the surgeons will determine which location and angle a bone plate should be implanted into the cranioface of a patient based on their domain experiences, to reconstruct the fragmentary or deformed cranioface.
Because a conventional bone plate is usually manufactured in an injection molding manner, the produced bone plate is of predetermined shape and size.
In general, surgeons often bend the conventional bone plate (which has predetermined shape and size) in a proper angle and direction by hands into a desired shape that fits to the area and shape of an injury part of the cranioface of the patient. Thus, the bent bone plate can be positioned on a proper location of the cranioface of the patient, allowing the broken bones of the cranioface of the patient to be fixed or repaired via the bent bone plate.
Since the structure, shape, spatiality and thicknesses of human cranioface are in a great complexity, as well as since the cranioface includes the supramaxilla and submaxillary that involve occlusion, eating, gums arrangement and facial looks, the conventional bone plate with inflexible shape and size can not properly fit to the injury part of the cranioface of the patient. This results in inconvenience in using the conventional bone plate. Moreover, since the conventional bone plate is manually bent by hands, the bent bone plate may not fully fit to the area and shape of the injury part of the cranioface of the patient, resulting in difficulty in accurately positioning the bent bone plate on the cranioface of the patient. As a result, the performance of craniofacial reconstruction is greatly affected.
Due to the problems stated above, the craniofacial surgery employing the conventional bone plate may require a longer healing time for patients. In a worse case, the patient who underwent the craniofacial surgery may have problems in occluding and chewing properly, or even have a disordered gums arrangement that leads to poor healing of the injured part. This affects the facial appearance of the patient negatively and makes the facial actions of the patient awkward. It takes a long time and several labionasal plastic surgeries for most patients to regain lip and palate functions.
U.S. Pat. No. 7,603,192 discloses another bone plate manufacturing method that establishes one or more 3D graphical models using a CT scan and physical model. The method generates X, Y and Z planes for each 3D graphical model so that complete 3D graphical models of an affected part and a bone plate can be obtained. The method finally compares the 3D graphical models and accordingly creates a design of the bone plate that can be well-fitted to the affected part of the patient.
However, the above bone plate manufacturing method merely improves the fitting between the bone plate and the bone surface of the affected part without taking some important factors into consideration, such as the mechanical factor associated with the forces acted upon the bone plate and the affected part, the craniofacial appearance and occlusion function etc. Therefore, the bone plate manufactured by the above bone plate manufacturing method can only be applied to limb bones which have a regular shape and relatively even thickness (compared to human cranioface) and do not suffer complex forces.
Since a human cranioface has a much more complex structure and can suffer multiple forces, the craniofacial bones tend to have compound fractures. Thus, the bone plate manufactured by the above conventional bone plate manufacturing method, which does not take the mechanical factor between the bone plate and the affected part into consideration, is not applicable to craniofacial reconstruction. This is because the bone plate is not able to provide sufficient accuracy in craniofacial reconstruction in such a complex craniofacial structure while the facial appearance and the functions of the supramaxilla and submaxillary are still maintained.